Process of making potash and structural materials and products thereof.



' V I ED STATES PATENT OFFICE;

An'rnun c. srnucmt-or WASHINGTON, ms'iiuc'r bEfCbLUMBIA.

success or Maxim ro'msn nun s'rnuc'runnr. unrsarsis nunrnonurxrs 'rnnnnor.

I 1,146,532, Specification of Letters Patent.

roma ne, I

T all u lzoin it-m ay concave: .Be it known that I, An'rr'miz Qt Srnxcnu, a citizen of the United States, residing at Washington, in the District of Columbia,

b'hav invented certain new "and useful In proi'ements in Processes of Makin Potash and. Structural Materials and roduct's' Thereof, of which the following is a specificaion.

1o. I his invention relates to processes of making potash and structural materials and products thereof; and it comprises a method wherein a potassi'ferous natural magnesi-an cement ioclt is heated and maintained at'a temperature above the cement making temperature to cause a sinterii g and anevolutionof potash 'fumes, the evolved potash is recovered and the residual hot plastic mass is shaped into structural forms or otherwise utilized; and itcomprises -the .product of said prdcest;' such product being a sintered natural cement rock, but not having-thee roperties of natural cement; all nsmoreully hereinafter set forth and as claimed.

-There.are many natural cement rocks 1 ii'hichire high in. potash and contain magnesia. and 1vich,--if burnt? at a sufliciently low tem rature, svilhform natural bement; 4 esubjoined compositionsmay be '80 taken as-typical'of this cla'ss of Silica 23.40 16:50 .Alumyinasmn u 16.172 8.76

'- ra a es a-- 4.09 1-1.9

-Alkalis 6.18 1x75 Ignition loss..- 21,40 35.80

burning cement'rock of said character cementitioils products which always be donpyjat a comparatively low temperature, the potash, which may amount to six'per cent. or more, 0! course remains with thematerial and persistsin tl-e cement,

produced whe re itis neitheruseful nor de-..

, silable. epotashrem a'ining in'the' msterialiproducesefllorescence and disintegration 0 the set cement. Its phresenoe is also undesirable duringjsetting'.

dinary clinker-making tern ra'tufs,-lsuch as are used in mid Po and cement, is

5 not practised with me of this character for,

timing ator v p watersgr'ays are jusedgthe waste gases from the reason that the products would not pass the usual standard tests for natural cement.

-Hard clinkered magnesian cement rock does not give cement in the-usual acce tance, of; the term. I'have however found t at by burning-these rocks at a high temperature,

while I cannot produce good quality-cement, I can nevertheless by suitably arrangingthe conditions fume oif, and recover th bulk of the potash' in Ya commercially-valuable value for other; urpose thancement to meet much of the costgof the operation. By

temperature for some time, it 'sinters and beginsto clinkerwithout actually fusing; down while the potash, the rockbeing basic,.'

,is evolved in the form offumes which may' be collected; WithQ-finely powdered material, such as is advantageously used (the' evolution of potash being, in a way, pro-j V 'POItlOIlal to the surface exposed as we'llas totime and temperature), there will generally bea considerable 'amountJof basic 89 dust, mostly lime, given off and thisserves to collect the potash fumes; The dust may be simply caught inja dust chamber-and the dust'marketed withthe. contained potash-as a fertiliier. Both potashand'lime are valuable ingredients of fertilizera The potash may of course be recovered by leaching the z dust; but this is ordinarily more expensive. and less advantageousthan marketing the dust as such. As stated,,the dust'is an advantageous typeof fertilizer.v Where potash, insteado'f potassiferousdust is sought, the evolution of dust should be suppressed as much as possible; and insu'ch anevent r the potash fumes may be caught in specially cohstructed fume chambers, and these chambers may be provided with watersprays It is often -us e ful to tre'atthe rock in the form of fragments" rathdhthan in powdered condition. ,For instanceyit may be cracked to pass. a;s creenof,16- meshes per square inch and separated into :fromtwo'to four sizes;

The'severa'lsizes are subjected separately to the heat treatment 'zBy calcination the frag ments'bec'ome porous and under sintering,

escapes from the porous 1 chnker. Where the b g operation are cooled and fan 4 draft in lieu of stack draft may housed. ll.

,Pat ntuaui w,1915; sp uunonaleu rn15.1911, SerialNo. 621,378.- l l a; form and can produce a- IGSldllQ'Of'SlllfiClGlll} m p which frees. the potash,'the. latter; many,

' 'no such special With collectionof the potash in evolved dust apparatus is required and stack draft may be used. Waste gases coming froma dust chamber after having deposited all the tash fume may be, and usually are, sti hot enou h, say 300 .to 400 C.,f0r stack draft. the evolution of the potash is a hot, plastic, granular or agglomerated material and beore loss of itsheat it may be compressed by briqueting appliances so as to form opentextured shape locks or bricks, useful as a building material, and particularly where 1 heat insulation is required. For structural urposes where little conductivity for heat is required, it is particularly advantageous to make these open-textured shapes, using no more pressure in the shaping operation material burnt in the Way described are not sufficient to make it a hydraulic cement, it isnevertheless sufiicientlycementitious to make an excellent road material, being the which it may have been used.

better for this purpose because of its deficiencyi-n some of the pro of cement clinker. It is har and -stony and as remaining after exposure to the potashevolving temperature is more or le agglutinated-to form-fa filomerates of various sizes suitable for roa lling. In the road it does not act like repared cement.', but vas it breaksup under t e wear and tear 'of-trafiic, the partlclesformed hydrate to airextent suflicient to act as a-bmde'r or matrix for the residue, or for other road stone with When applied to a road, in the course of time it forms a hard concrete-like surface, reuniting in a short time wherever broken or disturbed. Or if desired the cinder may be quenched with water as it comes from the furnace, and shi ped tothe point where it is to be used. ere it is mixed in any desirable proportion witli'broken stone and the mixture is then spread and well tamped or rolled. sprinkling is often advantagpous during the operation of surfacing. nder traflic the cinder becomes gradually active as a binder and in the course of a fewweeks produces an ideal surface which resists the sucking action of neumatic rubshapes are required, more rties required he residue after A her are; .The-use, of 'eum with this employed in 1,14e,eaa

surfacing material is often advantageous. The oil may be added at the start or it ma be sprinkled over the material after its bin ing qualities have beenrpartly or fully deve oped by trafiic and occasional wetting.

Any suitable type of apparatus may be ess. An or nary rotary cement kiln, 1n one'or more sections, so ara'tely fired if desired in the case of a p urality of sections, or having. one fired section communicatin with the unfired sections, may be employ While a rotary kiln is not suitable'for making cement from the character-of rocks contemplated in the present invention, since the temperatures in the clinkering zone incident to, and necessary for, firing with rformmg described propaerially suspended coal or fine fuel, are too such temperatures as these high, yet it is desirable in the which are required and present invention. The kiln may vided with ordinary or special types be rov of (F chambers, where catching the'potash in the,

dust is resorted to, or it may be provided with special fume chambers in can evolution of dust is repressed. The particular manner of collectingthe' evolved potash fume is not essential in .my invention,

though, as stated, for a variety of reasons it is considered much more advantageous to collect the fumes with calciferous ,dust.

With proper heatin to a sintering temperature, leaching the c inker to recover potash is generally not worth while. If thematerial is not sintered moistening makes it set and harden:

Various types of furnaces may be employed'without departing from my inverh tion. Furnaces heated by carbonaceous fuel are commonly best adapted-for the process inasmuch as the products of combustion pass through or over the charge and serve to furnish a carrier for the potash fumes as they are evolved. However, it is feasible and in some places economical to employ an electric furnace to bring about the essential reactions of theprocess. In using an electrical furnaceit is often advisable to pass a current of air or other. 8!! such as CO through or over the charge to away the potash as it isevolved. Pow coal is a convenient fuel, though natural oilor gas may be advantageously used where available, or producer gas may be used;

Where collecting the dust is resorted to, an'crdina'ry rotary inclined'cement kiln,

be used, the fincly'divided material fed into: its upper end and traveling downwardly in theusnaLmanner. It is advam' tageous to makerthe final or tion separate, g'ivingit but little tionto'retard the passe. of material throu h.i This is for e reason thatit is desire 1e to. retain the material under thev inclinemereinfluence of the high heat for some little time, or long enough to give opportunity for a maximum evolution of potash fumes,

without interfering with the feed through the calcining zone. The sintered material dropping from the end of the kiln may be received'i-n any suitable conveyer mechanism and conveyed to briqueti'ng apparatus,

'of which .any type may be employed. For

- clinker'coolers of the usual type. The hot waste gases carrying potash fumes and emergingfrom the upper end of the kiln maybelsent through ordinary or special dust chambers or potash collector's, as stated.

A typical cement rock useful in the present invention may carry 10 to 24 per cent.

silica, 5 to per cent. sesquioxids (ferric oxid and alumina), say 25 per cent. lime, 6' to 12 per cerit. magnesia and to 8 per cent. alkalis, of which the main portion is potash. The potash may run from o to 8 per cent; and from 75 to 95 per cent. of

this potash may be recovered under the present invention. 7

In lieu of using finely powdered material in a rotary kiln, coarsely powdered granulated or lump material may be used in either a'rotary or a stationary kiln. The kiln must however be run at a temperature markedly higher than those used in making natural cement or burning lime.

In any embodiment of the present process, the temperature must be high enough to cause a complete reaction between the lime of the rock and the silica and silicates such as will evolve or-set free the potash i-n fume form. Complete fusion should be' avoided since this would retard the evolution-of the fumes and diminish the yield. It is best therefore to use a temperature just below that of complete fusion; one at which the material becomes soft and semi-plastic but does not flow. If discharged in this condition, after evolution ofthe potash, it is in ideal condition for making briquets or blocks of reat mechanical strength.

ith many rocks high in magnesia, the calcining operation produces a free disinteg ration with the production of powder, economizing in the disintegrating operation since in=using a rotary the material may be fed into the upper end in coarse form and become fine in its progress. As the material becomes freely, porous in' the calcining operation, this may be reliecLupon in using fragmental-y material togiv'dthe necessary stir-- ;'but in such cement rock, heating to a. pomt justbelow.

face for evolution of, case more time must be given in the clinkering operation. In a similar manner, other cementitious rocks containing volatilizable constituents may be treated to recover such constituents and at the same time to yield residues suitable for the manufacture of 79 briquets or blocks as above described. For example, phosphorite or other phosphate bearing rock may be burned at temperatures too high to yield a good cement, phosphoric anhydrid being evolved and recovered, and

a residue being obtained which is semiplastic at the clinkering temperature employed, and which may be molded into any desired form while in this condition. Or the sintered mass may be allowed to cool in 80 irregular clinker form and used as road. making material as before described. 'Addition of silicious material to such rock, where the silica content of the rock is relatively low, is often desirable to facilitate evolution 86 of phosphoric anhydrid, since silica displaces phosphoric anhydrid in the reaction.

lVhat I claim is:

1. The process of producing plastic ma.- terials which comprises heating a natural 90 cement rock containing potash to a tempera:-

ture above the sintering point of the same, malntalmng the same at such temperature under suitable conditions for causing 'an evolution of potash until the major part of such potash is evolved, and compressing the hot plastic residue into shaped masses.

2. The process of treating materials which comprises heating a natural cement rock containing potash to a temperature above the sintering pbint'of the same, and maintaining the same at such temperature under sui able conditions for causingan evolution of pot-- ash until the major part of such potash is evolved, and the material is converted into a sintered product.

3. In the process of treating rocks for the manufacture of structural blocks, the process which comprises disintegrating a fusible rock, heating the material in the disintegrated form to a point just below the fusing temperature and pressing thesintering material into shaped blocks.

4. 'In the process of treating rocks for the manufacture of structural blocks, the process- 5' which comprises disintegrating a fusiblev v rock, heating the material in the disintegrated form to a point just below the fusing temperature and pressing the sinteringmaterial into open-textured shaped blocks. 129' v 5. In the process of treating rocks for the manufacture of structural blocks, the process which, comprises disintegrating a natural cement rock, heatingtoa point just below the fusing temperature and pressing thesin- .1"

term? material into shaped blocks.

the fusing temperatureand pressing the sintermg material into open-textured shaped lution of fume and dust.

8. As a new article of manufacture, an

open-textured block composed. of granules of sintered magnesian cement rock cohering at their meeting faces by a-fused union.

9. As a new article of manufacture, an open-textured block composed of granules Ocplce otthh patent may be obtained for live cents each,

of sintered cement rock 'cohering at their meeting faces by a fused union.

10. As a new article of manufacture a sintered natural cement rock existing in granules, said material having the approximate composition of a calcined rock of the same nature but not having the properties of natural cement.

In testimony whereof, I aflix my signature in the presence of witnesses.

ARTHUR C. SPENCER.

Witnesses:

K. P. McEuxor, o. W. Fowm.

by addressing the cclnlutcncr of htenti,

Washington, D. O. 

